NOAA Climate portal page allows has the most comprehensive accessible up to date and historic information. You can read out over any time period from 1900 to the present.

NOAA Annual GHG Index. The Annual Greenhouse Gas Index (AGGI ) is the ratio of the total radiative forcing due to long-lived greenhouse gases compared to 1990. This is the single best metric for assessing the climate. ​

The United States National
oceanic and atmospheric Administration which is under the US Department of
commerce is the top source of global climate change information relating to
both the United States and to the world.